Art of spray drying



April 30, 9- w. s. BOWEN 1,711,306

ART OF SPRAY DRYING Filed July 1, 1927 2 Sheets-Sheet 2 INVENTOR WILLIAMSPENCER BOWEN BY ATTCIRNEY April 1929- w. s. BOWE N 1,711,306

ART OF SPRAY DRYING File July 1, 1927 2 Sheets-Sheet 1 1&1

ATTORNEY of the nozzle producing the same.

Patented Apr. 30, 1929. V

pirEo STATES I 1,711,506 PATENT orr cn- WILLIAM srnncnn rowan; or wnsmm,NEW annsnx.

in or SPRAY name.

Application .flled July 1,

ing medium employed, thereby not only providing for a better product buteffecting economy of operation. y

In carrying out the invention, provision is made'for subjecting theincoming spray of solid-containing liquid in finely divided or atomizedcondition to a series of radially dis osed jets of the heated gaseousmedium, sai jets circumscribing the incoming spray and being locatedentirely below the orifice The said spray and circumscribing jets arelocated at the upper portion of a drying chamber and the driedpowderproduct will be deposited on the bottom thereot from which, inaccordance with the invention, it is removed through an opening thereinby "a novel collecting scraper member rotatable over said bottom andshaped toconcentrate the same into an e of the arrows.

. and h oithe fines from t area substantially equal to that of the saidopening, discharging the same therethrough, for example, into a suitablevalved hopper or the like associated with the bottom of the chamber. v

The nature of the invention, however, will best be understood whendescribed in connekeltipin with the accompanying drawings, in ,.W 0 2Fig. 1 is a vertical section of the desiccating tower or chamber inwhich the desiccating action is to be conducted, portionsof the towerwall being broken away to disclose the interior. f i

Fig. 2 is a plan view with a portion broken away to disclose theinterior.

Fig. 3 is a line 33, Fig. 1, and looking in the directionReferrmg-to-the draWingsJ O designates a shell providing a chamber ortower suitably a constructed and of capacity to conform with theoperations in view. As shown,,the tower comprises an inner shell 11forming a cylindrical chamber extending from the top of the towertoward. the bottom 12, the annular space 13 formed betwe'enthe outershell 10 and the inner shell 11 constituting an exhaust chamber for thes ent efiluent gases e powder product rectly introduced into the casinghorizontal section taken on the 1927; Serial No. 208,837.

as may be carried therewith. 'Suitable guide vanes 14 may-also beprovided .at the bottom of the said exhaust chamber 13 for the pur poseof evenly distributing the exhaust gases which are conducted therefromto the space 13 and thence removed from the tower through an exhaustduct 15.

Provision is made to supply the tower 10 I at its upper portion with aheated gaseous medium, as air and at a suitable temperature, forexample, through a flue or duct 16. An adequate volume of this gaseousmedium is to be supplied to the tower and may be provided in any wellknown manner, either by establishing a pressure thereon or by inducingafiow thereof through suitable exhaust apparatus (not shown) v-all ofwhich, however, is well understood 'and forms no particular part of thepresent invention.

The invention relates more especially to the manner in which thisincoming heated gaseous medium is'applied to the incoming 1 spray of thesolid containing liquid to be desiccated. The latter is introduced,generally, axially of the casing 11 through a suitable spray nozzle orlike device 20, which latter is connected Ewith a source of supply (notshown) by means of a suppl' ipe 21 having a controlling valve 22 inclu e'therein. Instead of the incoming aseous medium together with the sprayof iquid being di- 11 as is the ordinary practice, the former 18introduced in a plane below'the orifice 23 of the spray nozzle andvolume of incoming heated asecus medium is divided into a pluralityradially directed towardthe spray from said nozzle and circumscrihe thesame.

To this end, the to iofthe tower is provided with a distributing casing25 secured also in manner such that the jets which are thereon below theorifice of said spray nozzle,

and said casing is interrupted .to provide a circumferential annularchamber 26 into which the duct or flue 16 discharges. The

said casing, furthermore, has an axial open ing 27 therethrouigh forallowing the spray from the s ray nozzle to pass; and said opening ispre erably expanding or flarin downwardly into the casin 1]. to accommoate the usual frusto-conical orm'of the spray from the spray nozzle.Between this axial opening through the casing 25 and the circumferentialchamber 26 is a number of vertical walls or guide vanes 28 which aredispmed radially therebetween and the top'and ttom of the distributingcasing to direct theflow of in coming eated gaseous medium as radialjets 'towar the said spray proceeding from the spray nozzle orifice 23.

"By this means, a-series of circumscribing Jets of the incoming gaseousmedium will be directed radially toward the body of the sprayin a planeat right angles to its axis and will thereby most effectively cause itsdesiccation, heating the same appreciably before the spray expands intothe chamber or' casing 11. It will be noted that these impingnecessitate frequent removal for cleaning of the same. Fluids within thenozzle and sensitive to heat, furthermore, will not become overheatedprior to the breakin -up of the same into spray, The impact 0 the heatedgaseous medium upon the spray particles makes also for an appreciableincrease in the rate of evaporation of the liquid therefrom;

and due to the converging nature of the use ous medium passages, theyform individual nozzles for increasing the velocity of the flow of saidmedium and the impact upon the spray articles resulting in a markedefiect upon 't e rate of evaporation as aforesaid; also, in view of thecircumscribing nature of these jets, the said medium tends to be driveninto the axis of the spray 'cone .to further enhance thedesiccatingaction.

As stated, the mixture-ofidried material and gaseous heating mediuinthen passes through the chamber 11, the former dropping intothe bottom12 of the casing 10 and the latter being withdrawn as hereinbefores'etiorth.

Means are indicated also forthe disposal of the powdered materialaccumulating on the bottom 12, as in the provision of a scraper arm 30extending substantially from the'cem ter to circumference of said bottomand mounted for rotation thereover on a shaft 31 pro ectmg therethroughand driven by a pulley 32 thereon from a suitable source of power (notshown). Moreover, the said scraper.

arm is of a design having a portion 33 between 1ts ends which is curvedsubstantially to a semi-circle, the remaining portions converg inggradually thereto from the respective ends. By this expedient, thepowder on the bottom 12 is directed to the semi-circular portion 33 assaid arm is swept over the bottom durin its rotation. Bottom 12,moreover, is provi ed with anopening 34- therethrough and of diametersubstantially equal to that of (35 the semi-circular portion 33 of thescraper arm 30. It willbe understood, therefore, that as said scraperarm portion 33 and the opening 34 register, the powder material will bedelivered through the latter and dis charged therefrom as into a valvedhopper .35 or like devicefor finally withdrawing the powdered material.

I claim: 1. A spray drying apparatus, comprising'a casing providing a'desiccating chamber, a distributing casing secured to the top thereoffor the heated gaseous medium, radiall disposed guide vanes providedtherein mter-- mediate the periphery and center of the sameso to afforda circumferential distributing cham' ber, radial guide chambers and acentral through-passage, and a spraynozzle associated therewith andhaving its orifice dis-' posed above the top of said casing coaxially s5withitssaid central through-passage. p l 2.- A spray drying apparatus,comprising a casing providing a desiccatin chamber, a distribhtingcasing secured to the top there'- of for the heated gaseous medium,radially disposed guide vanes provided therein extending between the topand bottom walls of said 7 casing intermediate the periphery and cen- Iter of the same to afiorda circumferential distributing chamber, radialguide chambers and j WILLIAM SPENCER B WEN.

